Laser projector

ABSTRACT

A laser projector includes a laser assembly, a beam combination mirror group and a phase delaying component. The laser assembly includes a red laser light emitting region, a blue laser light emitting region and a green laser light emitting region. Red laser light is polarized in a first direction, green laser light is polarized in a second direction, and blue laser light is polarized in a third direction. The beam combination mirror group combines the red laser light, the blue laser light and the green laser light. The phase delaying component is on a light emitting path of at least one of the red laser light, the blue laser light the green laser light, and changes a polarization direction of the at least one of the red laser light, the blue laser light or the green laser light before being output by the beam combination mirror group.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation application of U.S.application Ser. No. 16/689,908, filed Nov. 20, 2019, which is acontinuation application of International Application No.PCT/CN2019/112480, filed on Oct. 22, 2019, which claims the prioritiesof the Chinese patent application No. 201910214208.6 filed on Mar. 20,2019, the Chinese patent application No. 201910214780.2 filed on Mar.20, 2019 and the Chinese patent application No. 201910539489.2 filed onJun. 20, 2019, the contents of which are incorporated herein byreference in their entireties.

TECHNICAL FIELD

The present application relates to the field of laser projection displaytechnology, and in particular, to a laser projector.

BACKGROUND

The laser light source has the advantages of good monochromaticity, highbrightness and long service life, and is an ideal light source. As thepower of lasers increases to meet the certain requirements of industrialapplication, lasers are increasingly being used as illumination lightsources. For example, in recent years, lasers have been used inprojectors to replace mercury lamps as projection light sources. Inaddition, lasers have the advantages of small optical expansion and highbrightness as compared to Light Emitting Diode (LED) light sources.

Lasers may be classified into blue lasers, red lasers and green lasersaccording to the type of illumination, which emit blue, red and greenlaser light, respectively. The blue laser is first applied industrially,and the red and green lasers are limited by power, for example, if theemission power is less than 1 W, the brightness will be low, so thatthey could not have been applied for a long time. Therefore, most oflaser projection light sources appearing in the industry are hybridlaser light sources of monochromatic laser light (blue laser light) andfluorescent light excited by the blue laser light.

Laser light emitted by the lasers is linearly polarized light. The blueand green laser light is generated by using a gallium arsenideluminescent material, and the red laser light is generated by using agallium nitride luminescent material. Due to different luminescentmechanisms of different luminescent materials, resonant cavities areoscillated in different directions during the light emission of the red,blue and green laser light. Specifically, the polarization direction ofred laser linearly polarized light differs from that of blue laserlinearly polarized light and green laser linearly polarized light in 90degrees. In addition, the red laser light is P-polarized light, and theblue and green laser light is S-polarized light.

When applying three-color laser for projection imaging, the picture onprojection screen media has a local color aberration phenomenon such as“color speckle” or “color patch”, which greatly affects the viewingexperience.

There is a need for a solution to solve the problem of the poor qualityof the projected image caused by the above-mentioned color aberrationphenomenon.

SUMMARY

The present application provides a laser projector capable of solvingthe problem of the local color aberration phenomenon present on athree-color laser projection image in the prior art.

In an aspect, the present application provides a laser projector,including a laser assembly comprising a red laser light emitting regionconfigured to output a red laser light, a blue laser light emittingregion configured to output a blue laser light, and a green laser lightemitting region configured to output a green laser light, where redlaser light is polarized in a first direction, the green laser light ispolarized in a second direction, the blue laser light is polarized in athird direction, and the first direction is different from at least oneof the second direction or the third direction; a beam combinationmirror group configured to combine the red laser light, the blue laserlight and the green laser light emitted by the laser assembly; a phasedelaying component, on a light emitting path of at least one of the redlaser light, the blue laser light or the green laser light, andconfigured to change a polarization direction of the at least one of thered laser light, the blue laser light or the green laser light beforethe red laser light, the green laser light, and the blue laser light areoutput by the beam combination mirror group.

In another aspect, the present application also provides a laserprojector, including a laser assembly configured to emit red laserlight, blue laser light, and green laser light, where red laser light ispolarized in a first direction, the green laser light is polarized in asecond direction, the blue laser light is polarized in a thirddirection, and the first direction is different from at least one of thesecond direction or the third direction; a beam combination mirror groupon an optical output path of the red laser light, the blue laser lightand the green laser light, the beam combination mirror group beingconfigured to combine the red laser light, the blue laser light, and thegreen laser light to generate a combined beam; a beam shaping componentconfigured to receive the combined beam emitted by the beam combinationmirror group and contract the combined beam; a diffusion wheelconfigured to rotate and diffuse the combined beam contracted by thebeam shaping component; an optical homogenizing component configured tohomogenize the combined beam diffused by the diffusion wheel; a lightvalve configured to receive a driving signal, modulating the combinedbeam homogenized by the optical homogenizing component, and output themodulated combined beam to a projection lens; and a phase delayingcomponent on an optical path before the modulated combined beam isoutput to the projection lens and configured to change a polarizationdirection of at least one of the red laser light, the green laser lightand the blue laser light.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a structure of a laser projectoraccording to one or more embodiments.

FIG. 2A is a schematic view illustrating a DLP projection architectureaccording to one or more embodiments.

FIG. 2B is a schematic view illustrating a circuit architecture of a DLPprojection system according to one or more embodiments.

FIG. 3A is a schematic view illustrating an ultra-short-throw projectionimaging optical path according to one or more embodiments.

FIG. 3B is a schematic view illustrating an ultra-short-throw projectionsystem according to one or more embodiments.

FIG. 4A is a schematic view illustrating an optical structure of a lightsource unit according to one or more embodiments.

FIG. 4B is a schematic view illustrating output timing of a light sourceunit according to one or more embodiments.

FIG. 4C is a schematic view illustrating a structure of anultra-short-throw projection screen according to one or moreembodiments.

FIG. 4D is a graph illustrating a change in reflectivity of theprojection screen in FIG. 4C to projection beams, in accordance with oneor more embodiments.

FIG. 5A-1 is a schematic view illustrating a structure of a laserprojector according to one or more embodiments.

FIG. 5A-2 is a schematic view illustrating a structure of a light sourceunit in FIG. 5A-1;

FIG. 5A-3 is a schematic view illustrating a cross-sectional structureof the light source unit in FIG. 5A-2 in accordance with one or moreembodiments.

FIG. 5B is a schematic view illustrating a structure of a laser assemblyin FIG. 5A according to one or more embodiments.

FIG. 5C is a schematic view illustrating a package structure of thelaser assembly in FIG. 5A according to one or more embodiments.

FIG. 5D is a schematic view illustrating a structure of a light sourceunit according to one or more examples of the present applicationaccording to one or more embodiments.

FIG. 5E is a schematic view illustrating a structure of another lightsource unit according to one or more embodiments.

FIG. 6A-1 is a schematic view illustrating a structure of a half-waveplate according to one or more embodiments.

FIG. 6A-2 is a schematic view illustrating the principle of a change ina polarization direction by 90 degree according to one or moreembodiments.

FIG. 6A-3 is a schematic view illustrating polarization directions ofP-polarized light and S-polarized light according to one or moreembodiments.

FIG. 6A-4 is a schematic view illustrating a rotation configuration of awave plate according to one or more embodiments.

FIG. 6B is a schematic view illustrating circularly polarized lightaccording to one or more embodiments.

FIG. 6C is a schematic view illustrating elliptically polarized lightaccording to one or more embodiments.

FIG. 7 is another schematic view illustrating a cross-sectionalstructure of a light source unit of a laser projector according to oneor more embodiments.

FIG. 8A is another schematic view illustrating a structure of a lightsource unit of a laser projector according to one or more embodiments.

FIG. 8B is another schematic view illustrating a structure of anotherlight source unit of the laser projector according to one or moreembodiments.

FIG. 9A is another schematic view illustrating a structure of a lightsource unit of a laser projector according to one or more embodiments.

FIG. 9B is another schematic view illustrating a structure of anotherlight source unit of the laser projector according to one or moreembodiments.

FIG. 10 is another schematic view illustrating a structure of a lightsource unit of a laser projector according to one or more embodiments.

FIG. 11 is an exploded view illustrating a simplified structure shown inFIG. 5A-1 according to one or more embodiments.

FIG. 12A is a schematic view illustrating a plane structure of a rotarywheel according to one or more embodiments.

FIG. 12B-1 is a schematic view illustrating a cross-sectional structureof a light source unit shown in FIG. 5B-1;

FIG. 12B-2 is a schematic view illustrating a plane structure of adiffusion wheel according to one or more embodiments.

FIGS. 13A and 13B are schematic views illustrating a cross-sectionalstructure of the diffusion wheel according to one or more embodiments.

FIG. 14 is another schematic view illustrating a structure of a laserprojector according to one or more embodiments.

FIG. 15 is a schematic view illustrating an optical path of a laserprojector according to one or more embodiments.

FIG. 16 is another schematic view illustrating an optical path of alaser projector according to one or more embodiments.

DETAILED DESCRIPTION

FIG. 1 is a schematic view illustrating a structure of a laserprojector. According to the function of an optical system, the laserprojector includes a light source unit 100, a lighting system 200, and alens unit 300. The light source unit 100 and the lighting system 200 mayalso be referred to as an optical engine.

The lighting system 200 contains an optical modulator which is a corecomponent of the system. The optical modulator, also known as a lightvalve, may be transmissive Liquid Crystal Display (LCD), Liquid Crystalon Silicon (LCOS), or Digital Micro-mirror Devices (DMD) chip. The DMDchip is applied to a Digital Light Processing (DLP) projectionarchitecture.

FIG. 2A illustrates a DLP projection architecture, in which the DMD chipis a core component of the overall projection architecture. Thefollowing is an example of the application of a monolithic DMD chip. ADMD chip 220 is a reflective light valve component. After passingthrough an illumination optical path 210 in front of the DMD chip 220,an illumination beam output by the light source unit 100 conforms to anillumination size and incidence angle of the DMD chip 220. A surface ofthe DMD chip 220 may include thousands of micro-mirrors, each of whichmay be individually driven to deflect. For example, the DMD chipprovided by TI (Texas Instruments) may be deflected by plus or minus 12or 17 degrees. Light reflected by a positive deflection angle is calledON light, and light reflected by a negative deflection angle is calledOFF light. The OFF light is invalid light and usually hits onto ahousing or absorbed by a provided optical absorption device. The ONlight is valid light incident into the lens unit 300 and will be usedfor projection imaging.

The lens unit 300 includes a plurality of lens combinations, which maygenerally be divided into groups. For example, the lens unit 300 may bedivided into a front group, a middle group, and a rear group, or into afront group and a rear group. The front group is a group of lenses neara light emitting side of the projector, and the rear group is a group oflenses near a light emitting side of the optical modulator. In theultra-short-throw projection, the lens unit 300 is an ultra-short-throwprojection lens whose throw ratio is usually less than 0.3. Theultra-short-throw projection lens shown in FIG. 3A includes a refractivelens group 310 and a reflective lens group 320. The reflective lensgroup 320 may be provided as a curved reflector such that projectionbeams are obliquely projected upward onto a projection screen 400 forimaging after passing through the lens unit 300 as shown in FIG. 3B. Inother words, unlike the conventional light emitting way in which theoptical axis of projection beams in telephoto projection is located onthe vertical line in a projected image, the ultra-short-throw projectionlens may usually have an offset of 120% to 150% with respect to theprojected image.

Because the DMD chip has a small size, for example, the DMD chipcurrently provided by TI has a size of 0.66 inches or 0.47 inches, andthe projected image usually has a size of above 70 inches such asbetween 80 inches and 150 inches, the lens unit 300 achievesmagnification by hundred times and correct aberration to have a goodresolution, thereby presenting a high-definition projected image. Thedesign of the ultra-short-throw projection lens is much more difficultthan that of the telephoto projection lens.

In the ultra-short-throw projector, the vertical line of a light exitingsurface of the DMD chip 220 is parallel to but does not overlap theoptical axis of the lens unit 300. In other words, by biasing the DMDchip 220 to the lens unit 300, the beam emitted from the light exitingsurface of the DMD chip 220 is obliquely incident into the lens unit 300at an angle, and finally emits out obliquely upward from the lens unit300 after being transmitted and reflected by a partial region of aplurality of lenses.

DMD chip, as an optical modulator, is driven by an electric signal tomodulate a beam such that the modulated beam carries image informationand is finally enlarged by the lens unit 300 to form a projected image.

On the basis of the relatively fixed resolution of the DMD chip itself,in order to realize an image screen with higher definition andresolution, as shown in FIG. 3A, a vibrating mirror 230 may be disposedin an optical path of light emitted from the DMD chip to a lens. Thevibrating mirror 230 may be of a transmissive flat plate structure. Byone-dimensional vibration, the vibrating mirror 230 angularly shifts theimage beams that are successively transmitted there-through, so that thebeams of two adjacent images are imaged on the projection screen afterbeing overlaid in a staggered way. In this way, by using the visionpersistence effect of human eyes, the information of the two images isoverlaid into the information of one image, so that image detailsperceived by the human eyes are increased, which may be equivalent to animprovement on image resolution.

The vibrating mirror 230 may also perform two-dimensional movement, forexample, move in four positions of up, down, left and right to overlaythe four images together in a staggered way, thereby improving theresolution perceived by human eyes with the principle of overlapping theinformation as described above.

Whether two or four images are overlaid, the images for overlapping needto be decomposed by a high-resolution image in advance, and thedecomposition method needs to match the movement mode of the vibratingmirror so as to be correctly overlaid without image confusion.

The vibrating mirror 230 is typically disposed between the DMD chip 220and the lens unit 300. Beams traveling between the DMD chip 220 and thelens unit 300 may be approximated as parallel beams, and the parallelbeams may still maintain a good parallelism after being refracted by thevibrating mirror 230. However, a beam having a large divergence angle,after being refracted by the vibrating mirror 230, changes greatly inangles, which may cause unevenness in brightness or chromaticity whenthe two image beams successively passing through the vibrating mirror230 are overlaid.

FIG. 2B is a schematic view illustrating a circuit architecture of a DLPprojection system. As shown in FIG. 2B, the DLP projection system mayinclude an image processing chip 201, a DMD chip 220, and a DMD drivecontrolling chip 202. The image processing chip 201 decomposes an imageto be displayed into RGB three-color component images, and outputs asignal of each component image (R or G or B component image) to the DMDdrive controlling chip 202. In this way, the DMD drive controlling chip202 may convert the signal of the component image into a driving signalof the DMD chip 220 to drive the micro-mirrors of the DMD chip 220 fordeflection, and form the brightness of a certain primary color componentimage by the angle and the duration of the deflection of themicro-mirrors. After overlapping of multi-primary color component imageframes, a color image is formed using the vision persistence effect ofhuman eyes. It should be noted that, in the above circuit architecture,the DMD drive controlling chip 202 may also be integrated with the DMDchip 220.

Since the driving signals received by the DMD chip 220 are generatedrespectively based on the RGB three primary color components of theimage to be displayed, that is, when the DMD chip 220 receives a drivingsignal corresponding to the R primary color component, red light shouldbe received. Similarly, when the DMD chip 220 receives a driving signalcorresponding to a G or B primary color component, green or blue lightshould be received. Therefore, the projection light source needs tocooperate with the DLP system to synchronously output the projectionbeam of the color that should be received by the DMD chip 220.

Therefore, in the example above, the light source unit 100 is configuredto supply the lighting system 200 with an illumination light source.Specifically, the light source unit 100 supplies the lighting system 200with an illumination beam by chronologically outputting three primarycolor illumination beams in synchronization.

The light source unit 100 may also provide a non-chronological output.For example, when other types of optical modulators are applied, inorder to cooperate with a three-panel LCD light valve, light of threeprimary colors in the light source unit 100 may be simultaneouslyilluminated to output mixed white light. In the example above, the lightsource unit 100 outputs the light of three primary colorschronologically. However, according to the principle of three-colorlight mixture, human eyes may not recognize the color of light at acertain moment, and what is perceived is still the mixed white light.Therefore, the output of the light source unit 100 is also generallyreferred to as mixed white light.

As shown in FIG. 4A, the light source unit 100 includes a laser assembly110 and a beam shaping component 112. Beam shaping may include processessuch as combining, homogenizing, and contracting light, etc. This isbecause, on one hand, the optical modulator has size and anglespecifications for the reception of light spot, and on the other hand,the luminous efficiency, uniformity, coherence and other index in anoptical path system are also considered to ensure that the light sourceunit 100 may be configured to provide high-quality illumination beam.

In one example, the light source unit 100 emits laser beams of threecolors. The laser assembly 110 may be an independent laser assembly ofRGB three colors, or a package assembly including light emitting chipsof three colors. The light source unit 100 emits laser light of RGBthree primary colors in turn chronologically in accordance with thesynchronization control signals output from the DLP system. The timingdiagram may be seen in FIG. 4B.

It should be noted that in order to enhance the brightness of the lightsource, it is sometimes possible to add yellow light on the basis of thethree-primary-color laser light. For example, yellow light may beproduced by overlapping red and green light. In other words, based onFIG. 4B, there may be a period in which two-primary-color light issimultaneously output.

When applying the above-mentioned ultra-short-throw laser projector toprojection imaging, an ultra-short-throw projection screen is oftenmatched with high gain and contrast to better restore a high-brightnessand high-contrast projected image.

An ultra-short-throw projection screen, as shown in FIG. 4C, is aFresnel optical screen 400. The Fresnel optical screen 400 includes asubstrate layer 401, a diffusion layer 402, a uniform medium layer 403,a Fresnel lens layer 404, and a reflective layer 405 along the incidentdirection of projection beams. The Fresnel optical screen 400 typicallyhas a thickness between 1 and 2 mm, with the substrate layer 401occupying the largest proportion of thickness. The substrate layer 401also serves as a support layer structure for the entire Fresnel opticalscreen 400, and has a certain light transmittance and hardness.Projection beams are first transmitted through the substrate layer 401,then into the diffusion layer 402 for diffusion, and into the uniformmedium layer 403. The uniform medium layer 403 is a uniform medium toallow beams to pass through, and may be made of the same material as thesubstrate layer 401, for example. After the beams are transmittedthrough the uniform medium layer 403, they are incident into the Fresnellens layer 404. The Fresnel lens layer 404 concentrates and collimatesthe beams, and the reflective layer 405 reflects the collimated beams.Then the collimated beams are folded back from the reflective layer 405to sequentially pass through the Fresnel lens layer 404, the uniformmedium layer 403, the diffusion layer 402, and the substrate layer 401and are incident into user's eyes.

In the process of research, the applicant found that local coloraberration phenomenon will be present on the ultra-short-throw projectedimage of three-color laser light source, resulting in unevenchromaticity such as “color speckle” and “color patch”. One reason forthis phenomenon is that, on one hand, in the currently appliedthree-color laser, the polarization directions of laser beams ofdifferent colors are different. For example, a plurality of opticallenses, such as lenses and prisms, are usually provided in an opticalsystem, and the optical lens itself has a difference in transmittanceand reflectivity (hereinafter also referred to as transflectivity) ofP-polarized light and S-polarized light. For example, an optical lenshas a transmittance for P-polarized light greater than that forS-polarized light. On the other hand, due to the material and structureof the screen, with the change of incidence angle of theultra-short-throw projection beam, the ultra-short-throw projectionscreen will present a significant change in transmittance andreflectivity of beams in different polarization directions. For example,as shown in FIG. 4D, for a red projection beam, when the projectionangle is about 60 degrees, the reflectivity of the projection screen tothe red projection beam which is P-polarized light differs from that tothe red projection beam which is S-polarized light by more than 10percentage points through tests. The ultra-short-throw projection screenhas a higher reflectivity to P-polarized red light than to S-polarizedred light, which causes more P-polarized red light but less S-polarizedred light to be reflected into the human eyes by the screen. Suchphenomenon that the projection screen has a difference in transmittanceand reflectivity of red light in different polarization directions alsoexists with respect to other color light in projection beams. When thelight of the three primary colors is in different polarization states,after passing through the projection optical system and the projectionscreen, the obvious difference in transmittance and reflectivity of theprojection screen to light in different polarization states may causelight of different colors reflected into the human eyes by the screen tohave unbalanced luminous flux, eventually leading to presence of localcolor aberration phenomenon on the projected image, which is especiallynoticeable when a color picture is presented.

In order to solve the above-described problems, the present applicationproposes the following exemplary solutions.

FIG. 5A-1 is a diagram of a laser projector 10, in accordance with oneor more embodiments. The laser projector 10 includes a housing 101 and aprojection imaging system wrapped by the housing 101. The projectionimaging system includes a light source unit 100, a lighting system 200,and a lens unit 300. The light source unit 100 emits laser beams ofthree colors.

As shown in FIG. 5A-2, it is an example of the light source unit 100 inthe laser projector 10. The light source unit 100 includes a housing 150and a laser assembly 110. The light source unit 100 is a laser lightsource of three colors. The three-color laser beams are emitted from anopening 152 of the light source unit 100, and are incident into adiffusion unit 140 which is, for example, a diffusion wheel.

FIG. 5A-3 is an exemplary cross-sectional structural view of FIG. 5A-2.The housing 150 has a receiving cavity 151. The laser assembly 110 and abeam combination mirror group 120 are at least partially housed in thereceiving cavity 151. The receiving cavity 151 has the opening 152 alonga light emitting direction of the light source.

FIG. 5B is a schematic view illustrating a structure of a laser assemblyin FIG. 5A. As shown in FIG. 5B, the laser assembly includes a red laserlight emitting region 1103, a blue laser light emitting region 1102, anda green laser light emitting region 1101. Specifically, laser lightemitting chips of three colors are arranged in a matrix and packaged ina module. For example, an MCL (mean control limit) laser used in oneexample is in a 4×5 light emitting array. The laser assembly includes asubstrate 1110. The substrate 1110 is packaged with a plurality of lightemitting chips, and a collimating lens group may be disposed at a lightemitting surface of the laser assembly. The light emitting surface ofthe laser assembly has a plurality of light emitting regions, and beamsemitted by different light emitting regions have different colors. Forexample, green light is emitted from a row, blue light is emitted fromanother row, and red light is emitted from the remaining two rows. Theabove laser assembly packages the three-color light emitting chipstogether, and has a small volume, which is advantageous for reducing thevolume of a light source unit 100. The red laser light emitted by thelaser assembly is P-polarized light, and the green and blue laser lightemitted thereby are both S-polarized light.

It should be noted, the laser assembly is not limited to be arranged inthe above-mentioned 4×5 array, which may be arranged in other array,such as a 3×5 array or a 2×7 array, as long as laser beams of threecolors can be emitted.

In the laser assembly 110, a circuit board parallel to a light emittingsurface of a laser is surrounded on the outside of the laser to providea drive control signal for the laser. Moreover, as shown in FIG. 5C, thecircuit board has a flat plate structure, and the laser has pins 1111 onboth sides. The pins 1111 are respectively soldered or plugged ontocircuit boards 1113 a and 1113 b which are almost parallel to a planewhere the laser is. The circuit boards 1113 a and 1113 b may beintegrally formed and surround the outside of the substrate 1110 of thelaser assembly. Alternatively, the circuit boards 1113 a and 1113 b mayalso be two separate circuit boards that enclose the laser assembly 110.In this way, the packaged laser assembly may also be regarded as a flatplate structure, which is easy to install and saves space and is alsoadvantageous for miniaturization of the light source unit 100.

As shown in FIGS. 5A-2 and 5A-3, the laser assembly 110 may be fixed tothe housing 150 by screws, and will emits laser beams of three colorsinto the receiving cavity 151 inside the housing 150. Further, a phasedelaying component 130 and the beam combination mirror group 120 aredisposed within the receiving cavity 151 inside the housing 150 towardthe light emitting surface of the laser assembly.

A plurality of beam combination mirrors are disposed for the lightemitting region of each color of the laser assembly 110. The pluralityof beam combination mirrors forms the beam combination mirror group 120for combining laser beams from different light emitting regions.

In some embodiments, the blue laser light emitting region 1102 and thegreen laser light emitting region 1101 are disposed adjacent to eachother, and the phase delaying component 130 is disposed toward the beamsof the blue laser light emitting region 1102 and the green laser lightemitting region 1101, and is located on an output path of blue light andgreen light and in front of the beam combination mirror group 120.

The phase delaying component 130 is a wave plate corresponding to awavelength of a certain color, which affects the degree of change inphase of a transmitted beam by the thickness of grown crystal. In someembodiments, the phase delaying component 130 is a half-wave plate, alsocalled a λ1/2 wave plate, which may change the phase of beam transmittedthrough the wave plate by π, that is, 180 degrees, and rotate thepolarization direction thereof by 90 degrees, for example, P-polarizedlight is converted into S-polarized light or the S-polarized light isconverted into the P-polarized light. As shown in FIG. 6A-1, thematerial of the wave plate may be provided as a crystal. The crystal hasits own optical axis W, and the optical axis W is located in the planewhere the wave plate is. Thus, when the wave plate is disposed on theoptical path as shown in FIG. 6A-1, the optical axis W of the wave plateand the optical axis O of the light source are perpendicular to eachother.

As shown in FIG. 6A-2, a coordinate system is established with theoptical axis W of the wave plate. The P-polarized light has componentsEx and Ey in the coordinate system formed with the optical axis W and adirection perpendicular to the optical axis W. The components Ex, Ey maybe represented by a light wave formula. The P-polarized light may beregarded as a spatial synthesis of two-dimensional waves for componentsEx, Ey.

When the P-polarized light passes through the wave plate, its phase ischanged by π, that is, 180 degrees, and the phases of the components Ex,Ey each have a change amount of π. Thus, after the phases of light wavesb0, c0, and a0 for the original P-polarized light at a certain momentare changed by 180 degrees, the polarization positions of the twocomponents Ex, Ey in space are changed to form light waves b1, c1, anda1, thereby being converted into the S-polarized light. The change inspatial position of the light waves b0, c0, a0 and b1, c1, a1 are merelyillustrative.

After passing through the half-wave plate, the original P-polarizedlight is converted into the S-polarized light, and as shown in FIG.6A-3, polarization directions of the P-polarized light and theS-polarized light are perpendicular to each other.

In FIG. 5A-2, both the blue light and the green light emitted by thelaser assembly 110 transmit through the phase delaying component 130 andthen are incident into the beam combination mirror beam combinationmirror group 120. Further, as shown in FIG. 5A-3, the phase delayingcomponent 130 is fixed inside the housing 150 in a clamp fixing mannerwithout blocking the optical path.

The beam combination mirror group 120 includes a plurality of beamcombination mirrors, is configured to combine beams of different primarycolors, so as to exit the combined beam from the opening 152 of thelaser light source. As shown in FIG. 5A-3, the beam combination mirrorgroup 120 includes three beam combination mirrors 1201, 1202, and 1203which are sequentially disposed on the light transmission path of thelaser. Specifically, beam combination mirrors are disposed respectivelyon a light emitting path of corresponding color light emitting region toreflect the beam emitted from the corresponding color light emittingregion. The reflected beam propagates in a light emitting direction ofthe laser light source, and the respective color beams combine to formwhite light.

A plurality of beam combination mirrors and the light emitting directionof corresponding light emitting region may have an angle for reflectingthe beam emitted from the corresponding light emitting region to thelight emitting direction of the laser light source. For example, aplurality of beam combination mirrors are sequentially arranged towardthe light emitting direction of the laser light source, and at least onebeam combination mirror is configured such that a beam of correspondingcolor in other light emitting region may be transmitted through that theat least one beam combination mirror. In this way, the beam ofcorresponding color in other light emitting region and the beamreflected by the at least one beam combination mirror may be combinedand then emitted out along the light emitting direction of the laserlight source.

Specifically, angles between a light receiving surface of the first beamcombination mirror 1201, the second beam combination mirror 1202, andthe third beam combination mirror 1203 and the green laser light, theblue laser light, and the red laser light emitted from the lightemitting regions of the laser assembly may be configured to 45°±2°. Thefirst beam combination mirror 1201 is a reflector, and the second beamcombination mirror 1202 and the third beam combination mirror 1203 areboth dichroic filters. The first beam combination mirror 1201, thesecond beam combination mirror 1202, and the third beam combinationmirror 1203 are disposed in parallel to each other.

The phase delaying component 130 may be specifically half-wave plates130G and 130B. As shown in FIG. 5D, the half-wave plate 130G is disposedbetween a light emitting surface of the green laser light emittingregion 1101 of the laser and the first beam combination mirror 1201; andthe half-wave plate 130B is disposed between a light emitting surface ofthe blue laser light emitting region 1102 and the second beamcombination mirror 1202.

Specifically, the half-wave plate as the phase delaying component 130may be disposed in parallel to the light emitting surfaces of the greenlaser light emitting region 1101 and the blue laser light emittingregion 1102. Further, there may be one half-wave plate, and the size ofthe half-wave plate may be the same as that of the light emittingsurfaces of the green laser light emitting region 1101 and the bluelaser light emitting region 1102, so that beams of both of the twocolors can be received.

In some embodiments, the first beam combination mirror 1201, as areflector, reflects green light transmitted through the half-wave plate130G; the second beam combination mirror 1202 transmits green light andreflects blue light transmitted through the half-wave plate 130B; thethird beam combination mirror 1203 transmits green light and blue lightand reflects red light, so that the three primary color beams are outputin the same direction, that is, in a direction toward the opening 152 ofthe housing 150, and are combined to form a combined beam. The firstbeam combination mirror 1201, the second beam combination mirror 1202,and the third beam combination mirror 1203 are fixed via an integratedbase, which may reduce the cumulative tolerance of multiple structuresand is convenient for maintaining the same angle set among a pluralityof beam combination mirrors and mutual relative positional relationship.The phase delaying component 130 may also be fixed via an integratedbase.

In some embodiments, in the MCL packaged laser, there are two rows orcolumns of red laser beams. Correspondingly, the third beam combinationmirror 1203 is configured to receive two rows of red laser beams and hasa size larger than the first beam combination mirror 1201 and the secondbeam combination mirror 1202 to be able to receive all beams output fromthe second beam combination mirror 1202.

The beams from the light source are incident into the beam shapingcomponent 112 after being combined, and the beam shaping component 112generally performs contraction, homogenization and other processing onthe beams.

The beam shaping component 112 may be provided as a focusing lens. Thebeams emitted from the laser assembly 110 are combined by the beamcombination mirror group 120 and then are emitted out in a directiontoward the opening 152 of the light source unit 100. In order to furtherobtain a beam having a small sized light spot, a focusing lens as thebeam shaping component 112 is also provided at the opening 152. Thefocusing lens is capable of converging the combined beam to reduce thespot size.

The diffusion unit 140 may be disposed on the light emitting path of thelight source, and the diffusion unit 140 is disposed on the lightemitting path of the focusing lens as the beam shaping component 112.The diffusion unit 140 may be provided as a rotatable diffuser forming adiffusion wheel structure. After being rotated and diffused by thediffusion unit 140, speckle of the beam may be dissipated to improve thebeam quality and reduce the speckle effect of the projected image. Thebeam diffused by the diffusion unit 140 may enter an opticalhomogenizing component 250 as shown in FIG. 5A-3. Specifically, theoptical homogenizing component may be provided as a light-pipe or afly-eye lens assembly.

As shown in FIG. 2B, the optical homogenizing component 250 is typicallyan optical homogenizing component for providing an illumination beam toan optical modulator, such as the DMD chip 220, in the lighting system200. The beam after passing through the optical homogenizing component250 further passes through a plurality of lenses, for example, a TIR(Total Internal Reflection) prism or an RTIR (Reflective total internalreflection) prism, and then is incident into the DMD chip 220 as anoptical modulator. The light emitting surface of the opticalhomogenizing component 250 and the light incidence surface of the DMDchip 220 are in a conjugate object-image relationship.

According to the above description, due to different luminescentmechanisms of different luminescent materials, the red laser light, theblue laser light and the green laser light are linearly polarized light,and the polarization direction of the red laser light differs from thatof the blue laser light and the green laser light in 90 degrees. In someembodiments, the red laser light emitted by the MCL laser assembly isP-polarized light, and the blue laser light and the green laser lightemitted by the MCL laser assembly are S-polarized light.

In a specific implementation, there may be one half-wave plate as thephase delaying component 130. Optionally, the half-wave plate 130 isdesigned according to the wavelength of the green laser light.Therefore, the green laser light, after being transmitted through thehalf-wave plate 130, is rotated in a polarization direction by 90degrees and converted to P-polarized light from the original S-polarizedlight. After the blue laser light is transmitted through the half-waveplate 130, since the wavelength of the half-wave plate does notcorrespond to the wavelength of the blue laser light, the blue laserlight is deflected in the polarization direction, but not by 90 degrees,so that the polarization direction of blue laser light transmittedthrough the half-wave plate 130 is close to the P polarizationdirection.

In a specific implementation, there may be two half-wave plates as thephase delaying component 130, which are set respectively with respect tothe wavelengths of the green laser light and the blue laser light, sothat the polarization directions of the green laser light and the bluelaser light may be changed by 90 degrees, that is, both of them areconverted into P-polarized light. Alternatively, there is one half-waveplate 130, but it is divided into two plated regions which are disposedrespectively with respect to the green laser light emitting region andthe blue laser light emitting region.

When there are two half-wave plates 130 or the half-wave plate 130includes two plated regions, as shown in FIG. 5D, they are disposedrespectively on the light emitting paths of the blue laser light and thegreen laser light. The half-wave plate 130B region and the half-waveplate 130G region may be fixed in the housing via a common supportstructure, and receive laser beams respectively from the blue laserlight emitting region 1102 and the green laser light emitting region1101 of the laser assembly. Specifically, the half-wave plate 130B isdisposed on the optical path of the blue laser light incident into thesecond beam combination mirror 1202, and the half-wave plate 130G isdisposed on the optical path of the green laser light incident into thefirst beam combination mirror 1201. When one half-wave plate is used foreach laser light, for example, the half-wave plates 130G and 130B, amore accurate phase delay may be performed as compared to a manner inwhich the blue laser light and the green laser light share the samehalf-wave plate for phase delay. Therefore, it is possible to obtaingreen polarized light and blue polarized light in the P polarizationdirection close to a theoretical value.

The same optical lens has the same transmittance and reflectivity to thesame P-polarized light or the same S-polarized light with differentwavelengths. The optical lens herein includes not only theaforementioned beam shaping component 112, i.e., the focusing lens, butalso a lens group on the illumination optical path in the lightingsystem 200 and a refractive lens group 310 in the lens unit 300.Therefore, when the beam emitted by the laser light source passesthrough the entire projection optical system, the difference intransmittance and reflectivity is the result of overlaying of the entiresystem, and becomes more apparent during projection imaging.

Before the phase delay is applied without a half-wave plate, especiallywhen the primary color light is linearly polarized light in P and Sdirections, whether an optical lens in an optical system or a projectionscreen has an obvious selective transmission to P-polarized light andS-polarized light. For example, as the incidence angle of the projectionbeam is different, the transflectivity of the projection screen toP-polarized light (red light) is significantly greater than that toS-polarized light (green and blue light). This causes the problem ofuneven local chromaticity of the projected image, that is, thephenomenon of “color speckle” and “color patch” appearing on theprojected image.

In some embodiments, by providing the half-wave plate 130 on the lightemitting paths of the blue laser light and the green laser light, inparticular, by providing the half-wave plates 130B and 130Gcorresponding to wavelengths respectively of the blue laser light andthe green laser light, the phase changes of the same deflection anglemay be performed respectively with respect to the polarizationdirections of the blue laser light and the green laser light, forexample, the S polarization direction is converted into the Ppolarization direction, thereby being the same as the polarizationdirection of the red laser light. Thus, when passing through the sameoptical imaging system and being reflected into the human eyes throughthe projection screen, the optical lens in the optical system has thesame transmittance to the blue laser light and the green laser lightwhich are converted into P-polarized light as the red laser light whichis P-polarized light, and the difference in reflectivity of theprojection screen to the laser light of three colors is also reduced, sothat the consistency of the light processing performed by the entireprojection system on the three primary color light is improved, therebyeffectively eliminating the local color aberration phenomenon present onthe projected image.

In some embodiments, when a half-wave plate for one color wavelength,for example, a half-wave plate for a green wavelength, is provided onthe light emitting paths of the blue laser light and the green laserlight, the green laser light is converted from S-polarized light intoP-polarized light and the blue laser light is converted close toP-polarized light after being transmitted through the half-wave plate,so that the consistency of the light processing performed by the entiresystem on the RGB three primary color light may be also improved,thereby greatly reducing the uneven chromaticity appearing on theprojected image locally. Moreover, the use of a half-wave plate tosimultaneously transmit beams in two color wavelength ranges may be moresimplified in structure settings. Further, the half-wave plate may alsobe provided for the blue wavelength. Correspondingly, the blue laserlight may change in the polarization direction by 90 degrees. Thepolarization direction of the green laser light does not change by 90degrees, but a large deflection also occurs with respect to the originalpolarization direction.

Since the transmittance of the optical lens in the optical system to theP-polarized light is generally greater than that to the S-polarizedlight, and the reflectivity of the projection screen to the P-polarizedlight is greater than that to the S-polarized light, the laser light ofRGB three color is P-polarized light by converting the blue laser lightand the green laser light that are S-polarized light into P-polarizedlight, which may improve the light transmission efficiency of theprojection beam in the entire system, thereby improving the brightnessand quality of the overall projected image.

In some embodiments, the blue laser light and the green laser light maybe combined first and then combined with the red laser light, and thehalf-wave plate may be disposed on an optical path before the blue laserlight and the green laser light are combined with the red laser light.Specifically, as shown in FIG. 5E, the half-wave plate 130H may bedisposed between the second beam combination mirror 1202 and the thirdbeam combination mirror 1203, and may transmit the combined beam of theblue laser light and the green laser light emitted from the second beamcombination mirror 1202. At this time, the half-wave plate 130H iscoated for one color wavelength instead of depending on the lightemitting regions, so that both the blue laser light and the green laserlight pass through the half-wave plate corresponding to one of theirwavelengths. In this way, the consistency of the light processingperformed by the entire system on the RGB three primary color light maybe improved, and the uneven chromaticity appearing on the projectedimage locally may be also improved effectively, the principle of whichis not described again.

FIG. 7 is another schematic view illustrating a cross-section structureof a light source of a laser projector according to one or moreembodiments. Compared with the light source shown in FIG. 5A-3, thephase delaying component is specifically a half-wave plate 130R, whichis disposed on the light emitting path of the red laser beam and islocated before the red laser beam is combined with the blue laser beamand the green laser beam. As shown in FIG. 7, it is disposed between ared laser light emitting region 1103 and a third beam combination mirror1203.

The half-wave plate 130R is provided corresponding to the red laserlight. Thus, the polarization direction of the red laser light may berotated by 90 degrees after passing through the half-wave plate 130R, sothat the red laser light is converted from P-polarized light intoS-polarized light.

Due to the difference in reflectivity of the ultra-short-throwprojection screen to P-polarized light and S-polarized light, and thedifference in transmittance of optical lenses in the projection opticalsystem to the P-polarized light and the S-polarized light, the luminousflux of the three colors is unbalanced, in particular, at certainprojection angles, resulting in the presence of local color aberrationphenomenon on the projected image received by human eyes finally.

In some embodiments, by providing the half-wave plate 130R on the redlaser light output path, the red laser light that was originallyP-polarized light is converted into S-polarized light so as to coincidewith the blue laser light and the green laser light in polarizationdirections. Thus, the projection optical system has reduced differencein transmittance to the red laser light, blue laser light and greenlaser light which are S-polarized light, and the ultra-short-throwprojection screen has substantially the same reflectivity to the redlaser light, blue laser light and green laser light which areS-polarized light. Therefore, the consistency of light processingperformed on each primary color light is improved, and the unevenchromaticity present on the projected image may be eliminated orimproved.

Since the transmittance of the ultra-short-throw projection screen andthe system optical lens to the P-polarized light is slightly larger thanthat to the S-polarized light, when the example above is applied, thered laser light is converted into the S-polarized light. Although itwill bring a certain light loss to the red laser light, since thestructure of the half-wave plate is provided only for the red laserlight, the consistency of polarization directions of the three-colorlaser beams is more easily realized while the structural arrangement issimplified.

A laser projector is provided in example above, which is applied to alight source unit structure as shown in FIG. 8A.

FIG. 8A is another schematic view illustrating a structure of a lightsource unit of a laser projector according to one or more embodiments.Unlike the light source units above, a red laser light emitting region,a blue laser light emitting region, and a green laser light emittingregion in the light source unit of this example are formed respectivelyof individually packaged laser assemblies. And each of the laserassemblies may be provided as a BANK laser (may also be referred to aslaser bank) or an MCL laser (Multi-Chip Laser).

As shown in FIG. 8A, the light source unit in a laser projector includesat least three sets of laser assemblies, each of which emits a laserbeam different from the other two ones.

A laser assembly 8110 emits a first color light, a laser assembly 8102emits a second color light, and a laser assembly 8103 emits a thirdcolor light.

The beams from the three sets of laser assemblies are combined by a beamcombination mirror group 8120. Referring to FIG. 8A, the beamcombination mirror group 8120 includes a fourth beam combination mirror8121 and a fifth beam combination mirror 8122. The fourth beamcombination mirror 8121 and the fifth beam combination mirror 8122 maybe both dichroic filters.

The fourth beam combination mirror 8121 transmits the first color laserlight and reflects the second color laser light to the fifth beamcombination mirror 8122. The fifth beam combination mirror 8122transmits the first and second color laser light and reflects the thirdcolor laser light. Thus, the laser light of the first, second and thirdcolor is combined to output via the fifth combining mirror 8122.

In a specific implementation, the first color is red, the second coloris green, and the third color is blue. Thereby, the fourth beamcombination mirror 8121 transmits the red light and reflects the greenlight, and the fifth beam combination mirror 8122 transmits the red andgreen light and reflects the blue light.

On an optical path of the green laser light incident into the fourthbeam combination mirror 8121 and an optical path of the blue laser lightincident into the fifth beam combination mirror 8122, half-wave plates8130 are disposed in parallel to the light emitting region for thecorresponding colors, the green laser light is transmitted through thehalf-wave plate 8130 and then incident into the fourth beam combinationmirror 8121, and the blue laser light is transmitted through thehalf-wave plate 8130 and then incident into the fifth beam combinationmirror 8122.

The forms and arrangements of the laser assemblies shown in FIG. 8A isdifferent from that of the laser assemblies shown in FIG. 5B, but theirprinciples of solving the local color aberration problem present on theprojection screen is same, and will not be described herein again.

Further, based on the laser assembly structures and arrangements shownin FIG. 8A, as another specific implementation, as shown in FIG. 8B, ahalf-wave plate for red color may be also disposed on a light emittingpath of the red laser light, and the red laser light is converted fromP-polarized light into S-polarized light. Please refer to the relateddescription in the application and details are not described hereinagain.

It should be noted that, the arrangement of the assemblies for the redlaser light emitting region, the blue laser light emitting region, andthe green laser light emitting region is merely exemplified above. Afterthe above-described arrangement is appropriately changed, the settingpositions of the half-wave plates are adaptively changed. For example,when the first color is blue, the second color is green, and the thirdcolor is red, the half-wave plates may be disposed respectively in frontof the fourth beam combination mirror 8121 into which the first colorlight is incident and in front of the fourth beam combination mirror8121 into which the second color light is incident, or in a combinedbeam of the blue laser light and the green laser light, that is, betweenthe fourth beam combination mirror 8121 and the fifth beam combinationmirror 8122. This example may also achieve the purpose of eliminatinguneven chromaticity present on the projected image locally, and theexamples are not described herein again.

FIG. 9A is another schematic view illustrating a structure of a lightsource unit of a laser projector according to one or more embodiments.Where a red laser light emitting region, a blue laser light emittingregion and a green laser light emitting region are formed respectivelyof laser assemblies that are individually packaged. Each of the laserassemblies may be provided as a BANK laser or an MCL laser.

The laser projector includes at least three sets of laser assemblies,each of which emits a laser beam different from the other two ones.

In some embodiments, a laser assembly 9110 emits a green laser light, alaser assembly 9102 emits a blue laser light, and a laser assembly 9103emits a red laser light, the emitted three-color laser light arecombined by an X beam combination mirror 9120. As shown in FIG. 9A, thered laser light emitting region, the blue laser light emitting region,and the green laser light emitting region are adjacent to each other andare arranged around the X beam combination mirror 9120.

The X beam combination mirror group 9120 is formed of two dichroicfilters in a center crossing manner, where the two dichroic filters area sixth beam combination mirror 9121 and a seventh beam combinationmirror 9122, respectively.

The green laser light emitted by the laser assembly 9110 is incidentinto the sixth beam combination mirror 9121 and is reflected by thesixth beam combination mirror 9121 to the seventh beam combinationmirror 9122. The blue laser light emitted by the laser assembly 9102 istransmitted sequentially through the sixth beam combination mirror 9121and the seventh beam combination mirror 9122. The red laser lightemitted by the laser assembly 9103 is reflected by the seventh beamcombination mirror 9122 to the sixth beam combination mirror 9121 and istransmitted through the sixth beam combination mirror 9121. Finally, thethree laser beams are combined by the X beam combination mirror group9120 including the sixth beam combination mirror 9121 and the seventhbeam combination mirror 9122.

Further, the light source unit further includes a phase delayingcomponent 930. Specifically, the phase delaying component 930 may be ahalf-wave plate. Referring to FIG. 9A, half-wave plates 930 are locatedrespectively in the optical paths of the blue laser light and the greenlaser light incident on the X beam combination mirror group 9120. Thus,the blue laser light and the green laser light are incident into the Xbeam combination mirror group 9120 after a change in polarizationdirection by 90 degree.

Alternatively, as another implementation, referring to FIG. 9B, thehalf-wave plate 930 may also be located on the optical path of the redlaser light incident on the X beam combination mirror group 9120. Thered laser light is incident into the X beam combination mirror group9120 after a change in polarization direction by 90 degree.

The laser projector with the light source unit shown in FIG. 9A and FIG.9B also achieve the technical purpose of eliminating or improving thelocal color aberration phenomenon present on the projected image, whichwill not be described herein again.

Further, some embodiments, the laser light emitting regions ofindividual forms assemblies, or the light emitting regions in which thelight emitting chips are arranged in an array, are generally provided ina rectangular shape. Correspondingly, the phase delaying component isdisposed on the light emitting path of one or two colors light, and itsshape is also rectangular. The long side and the short side of therectangular laser light emitting region are respectively parallel to thelong side and the short side of the rectangular light receiving regionof the phase delaying component.

Due to the high energy of the laser beam, optical lenses such as lensesand prisms may vary with temperature during operation. The opticallenses form internal stresses in manufacturing process, and the internalstresses are released as the temperature changes, to form a stressbirefringence. The stress birefringence may result in different phasedelays for beams with different wavelengths, which may be considered assecondary phase delays. Therefore, on the actual optical path, the phasechange of beam is based on the overlaying effect of the stressbirefringence of the optical lenses and the half-wave plate, and thedelay amount resulting from the optical lenses varies depending on thesystem design. When applying the technical solutions according to theseexamples of the present application, optionally, the secondary phasedelay caused by the actual system may be corrected to approach or reacha theoretical value of 90 degrees by which the polarization direction ofbeam changes.

The half-wave plate has an optical axis in its plane. As shown in FIG.6A-1, the optical axis W of the half-wave plate is spatiallyperpendicular to the optical axis O of the system, and the optical axisof the half-wave plate is parallel to the long or short side of thehalf-wave plate. When the solution of the example is specificallyapplied, as shown in FIG. 6A-4, the half-wave plate is configured torotate at a preset angle, such as C degree, along a direction of a longside or a short side of the rectangular half-wave plate as shown bydotted lines in the figure. After deflection by the above angle, theoptical axis of the half-wave plate also undergoes a deflection by aboutplus or minus C degrees, so that the phase change of beam is about 180degrees±2 C. degrees, and then is overlaid with the secondary phasedelay of the optical lenses in the system. Thus, the polarizationdirection of the beam is converted by about 90 degrees, which is closeto a theoretical value. In the various embodiments described above, Cmay take a value of 10.

In some embodiments, with respect to a three primary color light havingdifferent polarization directions, by providing a half wave plate on theoptical output path of the one or two colors light in the laserprojector, the polarization direction of the one or two colors lighttransmitting through the half wave plate is converted to coincide withthe polarization direction of other colors light, so that the differencein transmission of the projection optical system including the laserprojector, especially a plurality of optical lenses, to the red, blueand green laser light is reduced, the reflectivity of theultra-short-throw projection screen to the three primary color light isalso substantially consistent, the consistency of light processing oneach primary color light is improved, thereby the uneven chromaticitypresent on the projected image is eliminated or improved.

When half-wave plates are provided on the optical paths of the bluelaser light and the green laser light which are S-polarized light, afterthe half-wave plates convert their polarization directions respectively,all of the three primary color light in the system are P-polarizedlight, which may not only eliminate the uneven chromaticity present onthe projected image locally, but also increase the brightness of theprojected image to some extent.

Further, when a half-wave plate is provided on the optical path of thered laser light which is P-polarized light, after the half-wave plateconverts its polarization direction, all of the three primary colorlight in the system are S-polarized light, which may also eliminate theuneven chromaticity present on the projected image locally.

FIG. 10 is another schematic view illustrating a structure of a lightsource unit of a laser projector according to one or more embodiments.As shown in FIG. 10, the light source unit 100 includes a laser assembly110, and a beam combination mirror group 120 which is disposed on theoptical output paths of red laser light, blue laser light and greenlaser light, and the combining mirror group 120 is configured to combinethe red laser light, blue laser light and green laser light. Theposition and working principle of the related components have beendescribed in the above examples, and will not be described herein again.

The red laser light, blue laser light and green laser light, after beingcombined by beam combination mirror group 120, are incident into thebeam shaping component 112. In some embodiments, the beam shapingcomponent 112 may be a focusing lens, or a combination of focusinglenses and fly-eye lenses. The beam shaping component 112 is configuredto contract the combined beam, or to contract or homogenize the combinedbeam.

The combined three-color beam contracted by the beam shaping component112 is incident into a diffusion wheel 140, and the diffusion wheel 140rotates to diffuse and output the combined beam to an opticalhomogenizing component or a light collecting component 250.

The optical homogenizing component or the light collecting component 250may be a light-pipe, which may be provided as an entrance to anillumination optical path of the lighting system. The red laser lightemitting region, the blue laser light emitting region, and the greenlaser light emitting region in the laser assembly chronologically outputthe red laser light, the blue laser light, and the green laser light.The rotation period of the diffusion wheel 140 is consistent with thetiming period of the three-color laser light. The laser assembly appliedto the light source unit 100 is an MCL three-color laser array as shownin FIG. 5B, which will not be described herein again.

As shown in FIG. 10, the laser assembly is fixed on the housing of thelight source unit 100 via screws, and emits three-color laser beams tothe receiving cavity inside the housing. Moreover, a phase delayingcomponent and a beam combination mirror group are disposed within thereceiving cavity inside the housing toward the light emitting surface ofthe laser assembly.

Specifically, the beam combination mirror group 120 includes three beamcombination mirrors sequentially disposed on the optical transmissionpath of the laser, which are a first beam combination mirror 1201, asecond beam combination mirror 1202, and a third beam combination mirror1203, and are configured to combine beams of different primary colors tooutput the combined beam from the opening of the laser light source. Abeam combination mirror for respective colors is disposed on the lightemitting path of the light emitting region corresponding to the color,so as to reflect a beam corresponding to the light emitting region.Reflected beams are propagated in the light emitting direction of thelaser light source, and the respective color beams are combined to formwhite light.

A plurality of beam combination mirrors may have angles with the lightemitting directions of the corresponding light emitting regions, therebyreflecting the beams emitted from the light emitting regions to thelight exiting direction of the laser light source. For example, aplurality of beam combination mirrors are arranged sequentially towardthe light exiting direction of the laser light source, and at least onebeam combination mirror may transmit the beams emitted by other lightemitting regions. The beams emitted by the other light emitting regionsand a beam reflected by the at least one beam combination mirror iscombined to exit along the light emitting direction of the laser lightsource.

Specifically, an angle between the light receiving surface of the firstbeam combination mirror 1201 and green laser light from thecorresponding light emitting region of the laser assembly 110, an anglebetween the second beam combination mirror 1202 and blue laser lightfrom the corresponding light emitting region of the laser assembly 110,an angle between the third beam combination mirror 1203 and red laserlight from the corresponding light emitting region of the laser assembly110 may be all configured to 45°±2°. The first beam combination mirror1201 is a reflector. The second beam combination mirror 1202 and thethird beam combination mirror 1203 are dichroic filters. The first beamcombination mirror 1201, the second beam combination mirror 1202 and thethird beam combination mirror 1203 are disposed in parallel to eachother.

The laser light of each color also passes through the phase delayingcomponent before being incident into the beam combination mirror group120 for beam combination. As shown in FIG. 10, between the lightemitting region of each color laser light and corresponding beamcombination mirror, a quarter-wave plate corresponding to the color isprovided, which is a wave plate 2130G, a wave plate 2130B, or a waveplate 2130R respectively. The wave plate 2130G transmits the green laserlight emitted from the green laser light emitting region, and delays thephase of the green laser light by 45 degrees, so that the polarizationdirection thereof is rotated by 45 degrees and then incident into thefirst beam combination mirror 1201 which is a reflector. Similarly, thewave plate 2130B transmits the blue laser light emitted from the bluelaser light emitting region, and delays the phase of the blue laserlight by 45 degrees, so that the polarization direction thereof isrotated by 45 degrees and then incident into the second beam combinationmirror 1202. In addition, the second beam combination mirror 1202simultaneously transmits the green laser light reflected by the firstbeam combination mirror 1201 and reflects the blue laser light to form acombined beam, which incident into the third beam combination mirror1203. The wave plate 2130R transmits the red laser light emitted fromthe red laser light emitting region, and delays the phase of the redlaser light by 45 degrees, so that the polarization direction thereof isalso rotated by 45 degrees. The third beam combination mirror 1203reflects the red laser light whose polarization direction is changed,and transmits the blue laser light and the green laser light so as tocomplete the beam combination of the three primary color light.

FIG. 6B is a schematic view illustrating the principle of thequarter-wave plate for delaying the phase of beam. A coordinate systemis established by taking the P polarization direction and the Spolarization direction as coordinate axes. The polarized light inoriginal P polarization direction, after passing through thequarter-wave plate, is converted into polarized light P-t1, P-t2, P-t3which are in a plurality of polarized directions between the coordinateaxes at different times such as t1, t2, t3, thereby forming circularlypolarized light. Similarly, the S-polarized light, after passing throughthe quarter-wave plate, is also converted into polarized light S-t1,S-t2, S-t3 which are in a plurality of polarization directions betweenthe coordinate axes at different times such as t1, t2, t3, therebyforming circularly polarized light. That is, the polarization directionof the originally linearly polarized light is converted tomultidirectional over a period of time. Circularly polarized light isdeflected in a certain direction, such as clockwise. Therefore, althoughits polarization direction is multidirectional, it still conforms tocertain laws. Further, if the linearly polarized light passes through aquarter-wave plate that does not correspond to its own wavelength, itmay be converted into elliptically polarized light, as shown in FIG. 6C.

In conjunction with the example embodiment in FIG. 10, the green laserlight after passing through the quarter-wave plate 2130G and the bluelaser light after passing through the quarter-wave plate 2130B areconverted from the originally linearly S-polarized light into circularlypolarized light. The circularly polarized light has components in boththe P direction and the S direction which are changing sinusoidally withtime, and amplitudes of the components are equal. If the amplitudes ofthe components in the P direction and the S direction are not equal, itis converted into elliptically polarized light. The red laser light,after passing through the quarter-wave plate 2130R, is also convertedfrom the originally linearly P-polarized light into circularly polarizedlight. Thus, the originally linearly polarized light in differentpolarization directions is converted into circularly polarized light(not the same circularly polarized light), and has components with equalamplitude in the S direction and the P direction.

Since optical lenses in the projection optical system have a differencein transmittance to light (P-polarized light and S-polarized light) indifferent polarization directions, when the beam passing through theprojection lens 300 is projected onto the projection screen, due to thecharacteristics of the screen material, the difference in reflectivityto light in different polarization directions, especially to thelinearly polarized light in which the two polarization directions ofP-polarized light and S-polarized light are perpendicular in the lightsource unit in this example. The difference in polarization direction oflight from the light source, after passing through the system opticallens and being projected onto the projection screen, is overlaid withthe difference in transmittance and reflectivity to light in differentpolarization directions, resulting in local color aberration phenomenonsuch as “color speckle” and “color patch” present on a projected image,which seriously affects the image quality.

By providing the quarter-wave plate in the laser projector, the threeprimary color laser beams are respectively converted from linearlypolarized light into circularly polarized light through the quarter-waveplate. The circularly polarized light has a P-direction component and anS-direction component at different times, and the amplitude extremes ofthe two components are equal. In certain integration time, regardlessthe linearly polarized light is P-polarized light or S-polarized lightbefore, which has both the P-direction component and the S-directioncomponent after being converted into circularly polarized light.Moreover, for optical lenses, the difference in overall transmittance ofcircularly polarized light with different wavelengths is reduced. Thismakes it possible that when the combined beam of the three primary colorlaser beams is incident into the projection screen, although theprojection screen medium has different reflectivity to light indifferent polarization directions, since light with differentwavelengths has components in different polarization directions, thedifference in reflectivity of the projection screen to the light withdifferent wavelengths is reduced on the whole, thereby effectivelyimproving the local color aberration phenomenon present on a projectedimage due to the different polarization directions of the three primarycolor light.

In some embodiments, the wave plate 2130G may be disposed on the opticalpath of the green laser light incident into other beam combinationmirror, such as disposed between the first beam combination mirror 1201and the second beam combination mirror 1202, which may also achieve theabove technical effects and will not be described herein again.

In some embodiments, in order to decrease the number of quarter-waveplates or to simplify the installation structure, two or threequarter-wave plates may be simplified to one quarter-wave plate, whichmay be disposed for the wavelength of one color. In this way, light ofthis color is converted from linearly polarized light into circularlypolarized light after passing through the quarter-wave plate, and lightof the other one or two colors is converted from linearly polarizedlight into elliptically polarized light after passing through thequarter-wave plate. The elliptically polarized light also has componentsin the P direction and the S direction, but the component amplitudes aredifferent, as shown in FIG. 6C.

In some embodiments, after simplifying two quarter-wave plates for theblue laser light and the green laser light to one quarter-wave plate,the simplified quarter-wave plate corresponds to the wavelength of thegreen laser light, and may be disposed on the optical path of a combinedbeam of two colors laser light such as on the optical path of a combinedbeam of the blue laser light and the green laser light. For example, thequarter-wave plate may be disposed between the second beam combinationmirror 1202 and the third beam combination mirror 1203, as shown in FIG.10.

Alternatively, since the blue laser light emitting region and the greenlaser light emitting region are adjacent to each other, one largequarter-wave plate may be disposed for the two light emitting regions.At the same time, for the quarter-wave plate of the red laser beam,reference is still made to the original setting mode.

Alternatively, one quarter-wave plate is disposed on the optical path ofthe combined beam of the three-color laser light, such as disposed onthe optical output path of the beam combination mirror group 120.Alternatively, the diffusion unit 140 may have a structure of onequarter-wave plate, or the diffusion unit may be provided as a diffusionwheel. The light incidence surface of the diffusion wheel may beprovided with a wave plate crystal, and the light exiting surface of thediffusion wheel may have a diffusion microstructure.

Alternatively, when only one quarter-wave plate is disposed in the laserprojector, the quarter-wave plate may be disposed at a plurality ofpositions of the optical path of the combined three-color beams, such ason the light incidence surface or the light exiting surface serving asthe light-pipe of the optical homogenizing component 250, or on theoptical path from the DMD to the lens, which will not be described indetail herein. Reference is made to the following examples for detail.

Optionally, the quarter-wave plate is disposed on a position in theoptical path of the system at which the beam divergence angle is notlarge and the beam is approximate to a parallel beam.

When only one quarter-wave plate is disposed in the laser projector,optionally, the wave plate may correspond to a red laser wavelength or agreen laser wavelength.

In summary, in various embodiments, by providing a quarter-wave platebefore the laser beams of three colors are combined, or by providing thequarter-wave plate on the optical path of the combined beam of thethree-color laser light, the originally linearly polarized light isconverted into circularly polarized light or elliptically polarizedlight, so that the difference in transmittance of each primary colorlight in the projection optical system becomes small, and the differencein reflectivity of the primary color light to be reflected by theprojection screen is also reduced, thereby effectively reducing andimproving the local color aberration phenomenon present on a projectedimage.

Further, those skilled in the art should understand that when thedisplay problem of the projected image caused by different polarizationdirections of the three primary color light is solved according to thediscussed embodiments, the red laser light used as P-polarized light andthe blue and green laser light used as S-polarized light areexemplified, but the present application is not limited to thiscombination of P-polarized light and S-polarized light. In theapplication, those skilled in the art may make adaptive changesaccording to the color and polarization direction of the actual beam incombination with the core principles of the discussed embodiments, andthese changes should also be within the protection scope of the presentapplication.

FIG. 11 is an exploded view illustrating a simplified structure shown inFIG. 5A-1. As shown in FIG. 11, the laser projector includes a lightsource unit 100, a lighting system (not shown), and a lens unit 300.

Three-color laser beams emitted from the light source unit 100 passthrough a diffusion unit 140, which may also be referred to as rotatablewheel 140, and then enters an optical homogenizing component 250 such asa light-pipe. The light-pipe 250 collects and homogenizes a combinedbeam, and the homogenized beam is incident into the surface of a lightvalve 220 through other lenses and prisms of the illumination opticalpath. Thereafter, the light valve 220 reflects the projected beam intoprojection lens 300 for imaging and ultimately exhibiting the image onthe projection screen. Specifically, in some embodiments, the rotatablewheel 140 may include six color segments and three regions in total asshown in FIG. 12A. Each region is periodically located on the path of alaser beam of a certain color. Each region is provided with aquarter-wave plate corresponding to the wavelength of a color laserlight. For example, a region 11 is provided with a quarter-wave plate gfor transmitting green laser light; a region 12 is provided with aquarter-wave plate b for transmitting blue laser light; and a region 13is provided with a quarter-wave plate r for transmitting red laserlight.

The rotation period of the rotatable wheel 140 may coincide with theoutput timing of the light source. As the light source unitchronologically outputs three primary color laser beams, the threeprimary color laser beams are respectively incident into a quarter-waveplate region corresponding to laser light wavelength of different colorson the rotatable wheel 140, and the phase is changed after passingthrough corresponding quarter-wave plate. Further, since each primarycolor light passes through the movable wave plate, the degree of phasechange of each primary color light becomes different due to a differencein optical distance, so that the polarization directions of therespective primary color light are distributed in a plurality ofdirections. In this way, the three primary color light will no longerhave polarization characteristics, thereby effectively eliminating thelocal color aberration phenomenon present on a projected image caused bydifferent polarization directions of respective primary color laserlight.

Further, as another specific implementation of the structure of therotatable wheel 140, the rotatable wheel 140 is divided into threeregions, each including a light incidence surface I and a light exitingsurface O. For example, the light incidence surface I of a lighttransmitting substrate is provided with a crystal growth layer, and thelight exiting surface O thereof is provided with a microstructure, whichmay be formed by coating on the light-transmitting substrate.Alternatively, the substrate may also be made of a diffuser material,and its light exiting surface O is a light diffusion surface.

The application of the rotatable wheel 140 may not only depolarize thetransmitted laser beams with different wavelengths, but also diffuse thelaser beams of different colors to achieve the technical effect ofdissipating the speckles.

It should be noted that, for the sake of brevity, the rotatable wheel140 will be described by taking the three regions as an example. In someembodiments, the rotatable wheel 140 is not limited to be divided intothree regions. Further, the light source unit 100 may chronologicallyoutput not only three primary color light but also other colors lightbesides the three primary color light. For example, when the red laserlight emitting region and the green laser light emitting region aresimultaneously illuminated, the light source unit outputs yellow light.In addition to the three primary color light: red, green and blue light,there is also yellow light. The control over the red, green, and bluelaser light emitting regions is not limited to chronological outputeither. For example, the control timing of the red and green laser lightemitting regions may have an overlaying period in order to commonlyoutput a beam of corresponding color.

With respect to the structure of a plurality of regions of the rotatablewheel 140, such as more than 3 regions, a phase delaying componentsimilar to that in the above-described technical solution or a diffuserhaving a phase delaying effect is still used, which makes it possible todelay the phase of the transmitted laser beams of respective colors inmany ways, thus a linearly polarized light is depolarized, and the coloraberration phenomenon present on a projected image can be effectivelyeliminated or improved.

Further, the rotatable wheel 140 may be disposed on the optical outputpath of the beam combination mirror group 120 of the light source unit100. For example, the three primary color laser light, after beingcombined by the beam combination mirror group 120, passes through afocusing lens as the beam shaping component 112, for beam contractionand is incident into the rotatable wheel 140. Then, the beam exits fromthe rotatable wheel 140 first enters the light collecting component orthe optical homogenizing component 250 such as the light-pipe, and thenenters the illumination optical path of the light valve 220. Therotatable wheel 140 may be placed close to the light incidence surfaceof the light-pipe.

Further, the rotatable wheel 140 may also be disposed on the lightexiting surface of the light-pipe, and the light exiting surface of thelight-pipe and the light valve 220 are in a conjugate object-imagerelationship.

When the above-described structure of the rotatable wheel 140 isdisposed at other positions on the optical path of the combined beam ofthe three primary color laser light, the uneven chromaticity problempresent on a projected image may also be solved

In some embodiments, a plurality of phase delaying regions provided inthe rotatable wheel 140 may not be limited by the beam combinationstructure of the laser light source and the arrangement position of thephase delaying components. Therefore, the light source unit 100 may havea variety of light source architectures. For example, an MCL three-colorpackage laser or a BANK laser or the like is used as the light sourcearchitecture of the laser assembly.

In some embodiments, the rotatable wheel 140 may be provided with aphase delaying plate, or the light incidence surface of the rotatablewheel 140 may be made of a phase delaying plate crystal material, andthe light exiting surface thereof may be provided with a diffusionmicrostructure. As the rotatable wheel 140 rotates, the three primarycolor laser beams are transmitted through the phase delaying plate insequence. In a specific implementation, the rotatable wheel 140 may notsynchronize with the light output timing of the laser light source aslong as it keeps rotating to sequentially transmit the laser beams ofthree colors. The phase delaying plate on the rotatable wheel 140 may becircular, and the phase delaying plate may be configured to be ahalf-wave plate or a quarter-wave plate, or wave plates with differentthickness. Using the phase difference generated by the phase delayingplate, the wave plates with different thicknesses may delay the phase oflaser beams transmitted therethrough, thus a completely polarized lightis formed to exit, thereby depolarizing the original three primary colorlinearly polarized light and further effectively eliminating the localcolor shift phenomenon present on a projected image.

In some embodiments, in order to improve the definition of a projectedimage, a vibratable flat plate, i.e., a vibrating mirror may be disposedon the optical path of the light valve 220 to the projection lens. Thevibrating mirror may transmit beams. The phase delaying component mayalso act as a vibrating mirror to change the angle of the laser beamstransmitted therethrough through vibration, so that the beams of twoprojected images successively passing through the vibrating mirror aremisaligned, and thereby the contents of the two adjacent projectedimages are also misaligned and overlaid. The two images may bedecomposed from a high-resolution image. In this way, the display of thehigh-resolution image may also be realized by the low-resolution lightvalve 220, so that the details of the images perceived by a user arealmost identical to the contents of the high-resolution image, and thedefinition of the projected image is improved perceptually. The phasedelaying component may be provided as a quarter-wave plate or ahalf-wave plate, and may be configured with respect to a wavelength ofone of the three colors.

When the rotatable wheel 140 depolarizes the laser beams to solve thelocal color aberration problem present on a projected image, it ispossible to dissipate the speckles and further reduce or simplify thearrangement of individual phase delaying component and specklesdissipating component in the projection system, thereby facilitatingreduction in complexity of optical architectures and miniaturization ofthe laser projector.

In some embodiments, provision of a movable phase delaying component onthe optical output path of multi-color laser beams may depolarize thelinearly polarized light of different colors whose original polarizationdirections are perpendicular to each other, so that the consistency oflight processing performed by the optical lenses in the optical systemand the projection screen on each color light is improved, therebyeffectively eliminating the local color aberration phenomenon present ona projected image caused by different polarization directions ofmulti-color laser beams and further improving the display quality of theprojected image.

One or more embodiments of the present application provide a laserprojector, which will be described in conjunction with the foregoingFIGS. 5A-1, 5A-2, 5A-3, 5B, 5C, 5D, 5E, 6A-1, 6A-2, 6A-3, 6A-4, 6B, 6C,7, 8A, 8B, 9A, 9B, 10, 11, 12A and with reference to FIGS. 12B-1, 12B-2,13A, 13B, 14, 15, 16, and components that are substantially the same asthose in the embodiments discussed above will not be described hereinagain.

FIG. 11 is an exploded, simplified schematic view of FIG. 5A-1. As shownin FIG. 11, a three-color laser light emitted from a light source unit100 included in a laser projector is incident into a diffusion wheel140, and the diffusion wheel 140 rotates to diffuse the combined beam ofthe three-color laser light and outputs the diffused beam to an opticalhomogenizing component 250 such as a light-pipe. Next, the light-pipe250 collects and homogenizes the beam, and causes the homogenized beamto enter a surface of a light valve 220 after passing through theillumination optical path as shown in FIG. 2A. Then, the light valve 220modulates the beam from the illumination optical path in response to areceived driving signal, and causes the modulated beam to enter aprojection lens 300 and finally form an image on a projection screen.

Specifically, as shown in FIGS. 5A-2 and 12B-1, it is an exampleembodiment of the light source unit 100 of a laser projector 10. FIG.5B-2 is a cross-sectional structural view of FIG. 5B-1. The light sourceunit includes a housing 150 and a laser assembly 110. The light sourceunit 100 is a three-color laser light source, and laser beams of threecolors are emitted from the opening 152 of the light source unit 100.

The housing 150 has a receiving cavity 151. The laser assembly 110 and abeam combination mirror group 120 are at least partially housed in thereceiving cavity 151. The receiving cavity 151 has an opening 152 alonga light exiting direction of the light source. The three-color laserbeams are incident into a diffusion wheel 140 along an optical path fromthe opening 152. Phase delaying plates or phase delaying regions may bedisposed on the diffusion wheel 140 as shown in FIG. 12B-1.

The beams of three-color laser having different polarization directionsare incident into the diffusion wheel 140. Specifically, a phasedelaying plate may be disposed on the diffusion wheel 140. Specifically,FIG. 12B-2 is a schematic view illustrating a plane structure of thediffusion wheel. According to the incident timing of the three primarycolor laser beams, the surface of the diffusion wheel 140 may have threecolor segment partitions, which are respectively Sr, Sg, and Sb. In animplementation, the three partitions are each provided with a phasedelaying plate, or a whole phase delaying plate is provided and dividedinto three color segment partitions to respectively transmit laser beamsof three colors according to timing.

The phase delaying plate corresponds to a wavelength of a certain color,which affects the degree of change in phase of a transmitted beam by thethickness of grown crystal. In some embodiments, the phase delayingplate is a half-wave plate, also called a λ1/2 wave plate, which maychange the phase of beam of a corresponding wavelength of a colortransmitted through the wave plate by π, that is, 180 degrees, androtate the polarization direction thereof by 90 degrees, for example,P-polarized light is converted into S-polarized light or the S-polarizedlight is converted into the P-polarized light. When the phase delayingplate is a quarter-wave plate or a three-quarter wave plate, the beamwith the corresponding color wavelength transmitted through the waveplate may be converted from linearly polarized light into circularlypolarized light. A schematic representation of the circularly polarizedlight is shown in FIG. 6B.

As shown in FIG. 6A-1, the phase delaying plate or the wave plate isformed through the growth of crystal. The crystal has its own opticalaxis W, and the optical axis W is located in the plane of the waveplate. Thus, when the wave plate is disposed on the optical path asshown in FIG. 6A-1, the optical axis W of the wave plate and the opticalaxis O of the light source are perpendicular to each other.

In an implementation, as shown in FIG. 13A, the light incidence surfaceI of the diffusion wheel 140 is provided with a phase delaying plate,and the light exiting surface O thereof is provided with a diffusionmicrostructure. Alternatively, as shown in FIG. 13B, the light incidencesurface I of the diffusion wheel 140 is provided with a diffusionmicrostructure, and the light exiting surface O thereof is provided witha phase delaying plate. For example, a light transmitting substrate isprovided with a crystal growth layer on one surface and a microstructureon the other surface. The microstructure may be formed by coating on thelight transmitting substrate, or the substrate may also be made of adiffuser material. A side away from the wave plate is a light diffusionsurface.

There may be a variety of choices for the thickness of the phasedelaying plate, and optionally, it may be a quarter-wave plate or ahalf-wave plate or a three-quarter wave plate.

Further, a wavelength of a wave plate may be the wavelength of any ofthe three primary color light.

With respect to the process and principle of the movable phase delayingplate for phase change, reference may be made to the description ofexample as shown in FIG. 6B, and the details thereof are not describedherein again. In some embodiments, since the diffusion wheel 140performs a rotatable movement, the phase delaying plate also follows therotatable movement, so that the phase change of the linearly polarizedlight after passing through the movable phase delaying plate becomesrandom, and the change of its polarization direction is also random andmultidirectional. In other words, the movable phase delaying platedepolarizes the linearly polarized light, so that the consistency oflight processing performed by the optical lens in the optical system andthe projection screen on each color light is improved, therebyeffectively eliminating the local color aberration phenomenon present ona projected image caused by different polarization directions ofmulti-color laser beams and further improving the display quality of theprojected image.

Further, application of the diffusion wheel with the above-describedstructure may not only depolarize the transmitted laser beams withdifferent wavelengths, but also diffuse the laser beams of differentcolors so as to achieve the technical effect of dissipating thespeckles.

As shown in FIG. 12B-2, each region is provided with a quarter-waveplate for particular color laser light, where region Sg is provided witha quarter-wave plate g for transmitting green laser light, region Sb isprovided with a quarter-wave plate b for transmitting blue laser light,and region Sr is provided with a quarter-wave plate r for transmittingred laser light.

In some embodiments, the phase delaying plate may be provided only onthe rotatable wheel, and the diffusion microstructure is not provided,so that the structural arrangement on the rotatable wheel may besimplified. At this time, one or more phase delaying plates may beplaced on the rotatable wheel. As the wheel rotates, the three-colorlaser beams are sequentially transmitted through the phase delayingplate on the rotatable wheel, and the polarization directions of thetransmitted laser beams are converted multidirectionally. In a specificimplementation, the rotatable wheel may not be limited to synchronizewith the light output timing of the laser light source, as long as itkeeps rotating to transmit the laser beams of three colors sequentially.The phase delaying plate on the rotatable wheel may be circular. Thephase delaying plate may be configured to be a half-wave plate or aquarter-wave plate or wave plates with different thickness. Depending onthe movement form of the phase delaying plate, the wave plates withdifferent thicknesses may delay the phase of the laser beams transmittedtherethrough, thus a completely polarized light is formed to emit,thereby depolarizing the original three-color linearly polarized lightand further eliminating the local color aberration phenomenon present ona projected image.

FIG. 14 is another schematic view illustrating a structure of a laserprojector according to one or more embodiments. As shown in FIG. 14, amovable phase delaying component is disposed on an optical output pathof a light source unit, and the phase delaying component may be disposedat a plurality of positions on the optical path instead of on thediffusion wheel 140.

In an implementation, as shown in FIG. 14, the movable phase delayingcomponent may be disposed at position P1 in the combined light outputpath of the light source unit 100 and in front of the diffusion wheel140. Optionally, the movable phase delaying component is disposedbetween a beam shaping component and the diffusion wheel 140. In thisway, the phase delaying component may receive a contracted beam, and thesize of the phase delaying component may be smaller, thereby loweringcost and reducing the volume of the fixed structure and the drivingstructure. Moreover, depolarization is achieved before multi-colorlinearly polarized light in different polarization directions entersother optical lenses of the projection optical system, which contributesto reducing light loss in the system.

In another implementation, as shown in FIG. 14, the movable phasedelaying component may be disposed on the optical path that is incidentinto a light-pipe 250 after diffused by the diffusion wheel 140, forexample, at position P2 as shown in the figure. Optionally, the movablephase delaying component may be disposed at the light entrance to thelight-pipe 250. Because the light spot at this position has a smallsize.

Further, in another implementation, as shown in FIG. 14, the movablephase delaying component may be disposed at the light exit of thelight-pipe 250, for example, at position P3 as shown in the figure.After the multi-color laser beams are homogenized by the light-pipe 250,the energy distribution of the beams is already fairly uniform, which ismore favorable for the movable phase delaying component to convert thepolarization direction of the combined beam multidirectionally, and thedegree of change in polarization direction of each color light is alsorelatively consistent. A light exit of the light-pipe 250 and the lightentrance of the light valve, such as the DMD chip 220 are in anobject-image relationship.

The moving mode of the phase delaying component, in some embodiments,may include rotation, vibration, or other one- or two-dimensionalmovement.

The phase delaying component, in some embodiments, may be a half-waveplate or a quarter-wave plate or a three-quarter wave platecorresponding to a color wavelength of any one of the three-color laserbeams, or wave plates of other thickness.

Further, in another implementation, a vibratable phase delayingcomponent may be provided at position P4 as shown in FIG. 14, that is, avibratable phase delaying component may be disposed on the optical pathfrom the light valve such as the DMD chip 220 to the projection lens300. The vibratable phase delaying component may be of a flat platelight transmitting structure. Thus, in an aspect, with the vibratablephase delaying component, the polarization direction of the originalP-polarized light or S-polarized light may be made multidirectionally,so that the depolarization may be realized to solve the local coloraberration problem present on a projected image.

Meanwhile, the phase delaying component receives the projection beamreflected from the light valve 220, and the vibratable state of thephase delaying component causes the beams of two projected imagessuccessively passing through the phase delaying component to bemisaligned, so that the contents of the two adjacent projected imagesare also overlaid in a staggered way. The two images may be decomposedfrom a high-resolution image. In this way, the display of thehigh-resolution image may also be realized by a low-resolution lightvalve, so that the details of the images perceived by a user are almostidentical to the contents of the high-resolution image, and thedefinition of the projected image is improved perceptually.

FIG. 15 is a schematic view illustrating an optical path of a laserprojector according to one or more embodiments. For the laser projectorwith the optical path shown in FIG. 15, its light source unit includesat least three sets of laser assemblies, each of which emits a laserbeam different from the other two ones.

A laser assembly 8110 emits a first color light, a laser assembly 8102emits a second color light, and a laser assembly 8103 emits a thirdcolor light.

The light of the three sets of laser assemblies is combined by a beamcombination mirror group 8120. Referring to FIG. 15, the beamcombination mirror group 8120 includes a fourth beam combination mirror8121 and a fifth beam combination mirror 8122. The fourth beamcombination mirror 8121 and the fifth beam combination mirror 8122 maybe both dichroic filters.

The fourth beam combination mirror 8121 transmits the first color laserlight and reflects the second color laser light to the fifth beamcombination mirror 8122. The fifth beam combination mirror 8122transmits the first and second color laser light and reflects the thirdcolor laser light. Thus, laser light of the first, second and thirdcolor is combined to output via the fifth combining mirror 8122.

In a specific implementation, the first color is red, the second coloris green, and the third color is blue. Thereby, the fourth beamcombination mirror 8121 transmits red light and reflects green light,and the fifth beam combination mirror 8122 transmits the red and greenlight and reflects blue light.

After the beam combination by the beam combination mirror groupconsisting of the fourth beam combination mirror 8121 and the fifth beamcombination mirror 8122, the three-color laser beams having differentpolarization directions also pass through a diffusion wheel 8140, andthe diffusion wheel 8140 may adopt the same diffusion wheel structure asthe diffusion wheel 140 described above, so that the multi-colorlinearly polarized light with different polarization directions may bedepolarized using the rotatable phase delaying plate to solve the localcolor aberration problem present on a projected image, the process andprinciple of which are not described herein again.

In some embodiments, the diffusion wheel 8140 is still made of adiffuser material and has only a diffusion effect. Application of themovable phase delaying component disposed at a plurality of positions onthe optical path of the laser projector may also achieve the purpose ofdepolarizing the multi-color linearly polarized laser beams in differentpolarization directions, thereby solving the local color aberrationproblem present on a projected image.

FIG. 16 is another schematic view illustrating an optical path of alaser projector according to one or more embodiments. The substantiallysame components, connection relationship, working principles, and thelike with the above-discussed embodiments will not be described again.For the laser projector with optical path shown in FIG. 16, a greenlaser light emitted by a laser assembly 9110 is incident into a sixthbeam combination mirror 9121 and is reflected by the sixth beamcombination mirror 9121 to the seventh beam combination mirror 9122. Ablue laser light emitted by a laser assembly 9102 is sequentiallytransmitted through the sixth beam combination mirror 9121 and theseventh beam combination mirror 9122. A red laser light emitted by laserassembly 9103 is reflected by the seventh beam combination mirror 9122to the sixth beam combination mirror 9121 and is transmitted by thesixth beam combination mirror 9121. Finally, the three-color laser lightis combined by a beam combination mirror group 9120 including the sixthbeam combination mirror 9121 and the seventh beam combination mirror9122. After combining the beams by an X beam combination mirror group,the three-color laser beams having different polarization directionsalso pass through a diffusion wheel 9140. The diffusion wheel 9140 mayadopt the diffusion wheel structure as the diffusion wheel 140 describedabove, so that the multi-color linearly polarized light with differentpolarization directions may be depolarized using the rotatable phasedelaying plate so as to solve the local color aberration problem presenton a projected image, the process and principle of which are notdescribed herein again.

In some embodiments, the diffusion wheel 9140 is still made of adiffuser material and has a diffusion effect merely. While the movablephase delaying component disposed at a plurality of positions is appliedon the optical path of the laser projector, which may also achieve thepurpose of depolarizing the multi-color linearly polarized laser beamsin different polarization directions, thereby solving the local coloraberration problem present on a projected image.

In some embodiments, provision of a movable phase delaying component onthe optical output path of multi-color laser beams may depolarize thelinearly polarized light of different colors whose original polarizationdirections are perpendicular to each other, so that the consistency oflight processing performed by the optical lens in the optical system andthe projection screen on each color light is improved, therebyeffectively eliminating the local color aberration phenomenon present ona projected image caused by different polarization directions ofmulti-color laser beams and further improving the display quality of theprojected image.

Finally, it should be noted that the discussed example embodiments areused only to explain, but are not intended to limit the technicalsolutions of the present application. Although the present applicationis described in detail with reference to the foregoing examples, thoseskilled in the art should understand that the technical solutionsdescribed in the foregoing examples may be modified, or part or all ofthe technical features therein may be equivalently replaced. Thesemodifications or replacements do not deviate the essence ofcorresponding technical solutions from the scope of technical solutionsof the present application.

1. A laser projector, comprising: a laser assembly configured to emitred laser light, blue laser light, and green laser light, wherein thered laser light is polarized in a first direction, the green laser lightis polarized in a second direction, the blue laser light is polarized ina third direction, and the first direction is different from at leastone of the second direction or the third direction; a beam combinationmirror group on an optical output path of the red laser light, the bluelaser light and the green laser light, the beam combination mirror groupbeing configured to combine the red laser light, the blue laser light,and the green laser light to generate a combined beam; a beam shapingcomponent configured to receive and contract the combined beam emittedby the beam combination mirror group; a diffusion component configuredto diffuse the combined beam contracted by the beam shaping component;an optical homogenizing component configured to homogenize the combinedbeam diffused by the diffusion component; a light valve configured toreceive a driving signal, modulate the combined beam homogenized by theoptical homogenizing component, and output the modulated combined beamto a projection lens; and one or more phase delaying components disposedin an optical path from the laser assembly to the projection lens, andconfigured to change a polarization direction of at least one of the redlaser light, the green laser light and the blue laser light.
 2. Thelaser projector according to claim 1, wherein the diffusion component isa diffusion wheel.
 3. The laser projector according to claim 1, whereinthe one or more phase delaying components are disposed in a combinedoptical output path of the blue laser light and the green laser lightand before the combined beam of the red laser light, the blue laserlight and the green laser light is generated.
 4. The laser projectoraccording to claim 1, wherein the one or more phase delaying componentsare disposed in both a combined optical output path of the blue laserlight and the green laser light, and an optical output path of the redlaser light and before the combined beam of the red laser light, theblue laser light and the green laser light is generated.
 5. The laserprojector according to claim 1, wherein the one or more phase delayingcomponents are disposed in an optical output path of each of the bluelaser light and the green laser light and before the combined beam ofthe red laser light, the blue laser light and the green laser light isgenerated.
 6. The laser projector according to claim 1, wherein the oneor more phase delaying components are disposed in an optical output pathof the red laser light and before the combined beam of the red laserlight, the blue laser light and the green laser light is generated. 7.The laser projector according to claim 1, wherein the one or more phasedelaying components are disposed in each of an optical output path ofthe red laser light, an optical output path of the blue laser light andan optical output path of the green laser light, and the red laserlight, the blue laser light and the green laser light are output to thebeam combination mirror group after passing through the one or morephase delaying components.
 8. The laser projector according to claim 7,wherein the one or more phase delaying components comprise three phasedelaying plates which respectively corresponding to a red laser lightemitting region, a green laser light emitting region and a blue lightemitting region.
 9. The laser projector according to claim 7, whereinthe one or more phase delaying components comprise a phase delayingplate with three regions which respectively corresponding to a red laserlight emitting region, a green laser light emitting region and a bluelight emitting region.
 10. The laser projector according to claim 1,wherein the one or more phase delaying components are disposed in acombined optical output path of the red laser light, the blue laserlight and the green laser light.
 11. The laser projector according toany of claims 1, wherein the one or more phase delaying componentscomprise one or more of a half-wave plate or a quarter-wave plate. 12.The laser projector according to claim 1, wherein the one or more phasedelaying components comprise a movable phase delaying plate comprisingone or more of a rotatable phase delaying plate or a vibratable phasedelaying plate.
 13. The laser projector according to claim 1, whereinthe one or more phase delaying components are disposed between the beamshaping component and the diffusion component.
 14. The laser projectoraccording to claim 1, wherein the one or more phase delaying componentsare disposed on a light inlet of the optical homogenizing component. 15.The laser projector according to claim 1, wherein the one or more phasedelaying components are disposed in an optical path from the light valveto the projection lens.
 16. The laser projector according to claim 1,wherein the one or more phase delaying components are disposed on thediffusion component.
 17. The laser projector according to claim 1,wherein a light incidence surface of the diffusion component is providedwith the one or more phase delaying components and a light exitingsurface of the diffusion component is provided with a diffusionmicrostructure.
 18. A laser projector, comprising: a laser assemblyconfigured to emit red laser light, blue laser light, and green laserlight, wherein the red laser light is polarized in a first direction,the green laser light is polarized in a second direction, the blue laserlight is polarized in a third direction, and the first direction isdifferent from at least one of the second direction or the thirddirection; a beam combination mirror group disposed in an optical outputpath of the red laser light, the blue laser light and the green laserlight, the beam combination mirror group being configured to combine thered laser light, the blue laser light, and the green laser light togenerate a combined beam; a beam shaping component configured to receiveand contract the combined beam emitted by the beam combination mirrorgroup; an optical homogenizing component configured to homogenize thecombined beam; a light valve configured to receive a driving signal,modulate the combined beam homogenized by the optical homogenizingcomponent, and output the modulated combined beam to a projection lens;and one or more phase delaying components disposed in an optical pathfrom the laser assembly to the projection lens, and configured to changea polarization direction of at least one of the red laser light, thegreen laser light or the blue laser light.
 19. The laser projectoraccording to claim 18, wherein the one or more phase delaying componentsare disposed in the light emitting path of the red laser light, and thefirst direction of the red laser light after being transmitted throughthe one or more phase delaying components is changed by 90 degrees. 20.The laser projector according to claim 18, wherein the one or more phasedelaying components are disposed in the light emitting path of the greenlaser light and the light emitting path of the blue laser light, thesecond direction is equal to the third direction, and a polarizeddirection of each of the green laser light and the blue laser lightafter being transmitted through the one or more phase delayingcomponents is changed by 90 degrees.